Conventionally, an image forming apparatus, such as a printer, a photocopy machine, a facsimile device, a multifunction peripheral that includes a printer part and a scanner part, and the like, forms an electrostatic latent image by uniformly and evenly charge a surface of a photosensitive body and by exposing the charged surface, and forms a toner image by attaching developer (toner) on the electrostatic latent image. Then, an image is formed by transferring and fixing the toner image onto a sheet.
In such conventional image forming apparatus, a remaining toner amount detection mechanism is provided that detects a remaining toner amount (or amount of toner remaining) in a development device. The remaining toner amount detection mechanism is a rotation body that falls by own weight (free-falls) to a surface of the toner from a predetermined height when the remaining toner amount is low. The image forming apparatus detects the remaining toner amount by a length of time in which the rotation body that is the remaining toner amount detection mechanism free-falls (see JP Laid-Open Patent Application No. 2006-23537 (paragraphs 0021-0024)).
However, when the toner does not move, the rotation body in the development device may unnecessarily rotate.
One of objects of the present invention is to prevent the rotation body inside the development device from unnecessarily rotating.